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Python Python Basics Functions and Looping While Loops

William Elias
William Elias
9,472 Points
Posted by William Elias
William Elias
9,472 Points

why not use an "and" in the while loop instead of the "if"?

import sys

password = input("please enter the super secret password: ") attempt_count = 1 while (password != 'opensesame'): if attempt_count > 3: sys.exit("Too many invalid password attempts") password = input("invalid password, try again: ") attempt_count += 1 print("Welcome to secret town")

vs

password = input("please enter the super secret password: ") attempt_count = 1 while (password != 'opensesame') and (attempt_count < 3): password = input("invalid password, try again: ") attempt_count += 1 print("Welcome to secret town")

2 Answers

James Estrada
seal-mask
.a{fill-rule:evenodd;}techdegree
James Estrada
Full Stack JavaScript Techdegree Student 25,866 Points
James Estrada
.a{fill-rule:evenodd;}techdegree
James Estrada
Full Stack JavaScript Techdegree Student 25,866 Points

The problem for having 

while ((password != 'opensesame') and (attempt_count < 3)):

is that once the attempt_count no longer holds true, the loop will exit, and it will still print "Welcome to secret town"; which it should be printed only if the password was correct.

Philipp Räse
PLUS
Philipp Räse
Courses Plus Student 10,298 Points
Philipp Räse
Philipp Räse
Courses Plus Student 10,298 Points

Hello William,

first of all I felt free to convert your could a bit nicer to read

Your Code:

import sys

password = input("please enter the super secret password: ") 
attempt_count = 1 

while (password != 'opensesame'): 
  if attempt_count > 3: 
    sys.exit("Too many invalid password attempts") 

  password = input("invalid password, try again: ") 

attempt_count += 1 print("Welcome to secret town")

vs

import sys

password = input("please enter the super secret password: ") 
attempt_count = 1 

while (password != 'opensesame') and (attempt_count < 3): 
  password = input("invalid password, try again: ") 
  attempt_count += 1 

print("Welcome to secret town")

The mistake:

It would work with an and statement inside the while condition. But unfortunately you forgot an additional pair of brackets to surround your logic while-condition.

The solution:

The following code contains the missing brackets.

import sys

password = input("please enter the super secret password: ") 
attempt_count = 1 

while ((password != 'opensesame') and (attempt_count < 3)): 
  password = input("invalid password, try again: ") 
  attempt_count += 1 

print("Welcome to secret town")

I hope my answer helped you out.

Sincerly,

Phil

William Elias
William Elias
9,472 Points
William Elias
William Elias
9,472 Points

Thanks Phil!

I know there is more than one way to accomplish a task, but is there a more correct way here? Or will a later lesson make this question irelavent?

Philipp Räse
Philipp Räse
Courses Plus Student 10,298 Points
Philipp Räse
Philipp Räse
Courses Plus Student 10,298 Points

You're welcome William,

I think that I cannot answer your question that easy. It is much about personal preferences.

Craig Dennis mentioned in another curse the KISS-principle. Keep-It-Stupidly-Simple

But if you're writing comments that will describe your code, you and others will have it much easier understanding even complex lines of code.

The best code-structure is quite subjective and depends much on the relating project.

I would say, you better follow up the next lessons and develop your own view. I'm sure you'll do it great! :)